Reduction gearing unit



oct. 13, 1959 o. E. SMR. 2,908,187 4 REDUCTION GEARING UNIT Filled May 1 9, 1955 y 5 Sheets-Sheet l IN VEN 0R.

o. E. sA ARl 2,908,187 REDUCTION GEARING UNIT l s sheets-sheet 2j Filed may' 19' 1955 oct. v19, 1959 O. E. SAARl REDUCTION GEARING UNITy s sheets-'sheet s Filed Hay 19. 1955 United States Patent O REDUCTION GEARIN G UNIT Oliver E. Saar, Chicago, Ill., assignor to Illinois Tool Works, Chicago, Ill., a corporation of Illinois Application May 19, 1955, Serial No. 509,509

3 Claims. (Cl. 74665) The present invention relates to a novel reduction gearing unit, and more particularly to a novel skew axis reduction gearing unit.

An important object of the present invention is to provide a novel skew axis reduction gearing unit lincluding a plurality of concentric gear sections respectively driven by a plurality of worms, which gear sections and worms are constructed and arranged with respect to each other so as to provide a highly compact unit having a relatively high reduction ratio.

Another object of this invention is to provide Ia skew axis gearing unit of the above described type wherein the worms may be relatively easily positioned in proper meshing relationship With their -associated Worm gears.

Another object of the present invention is to provide a novel compact skew axis reduction gearing unit including a plurality of gear sections driven by a plurality of worms, which unit is highly efficient in operation, and is capable of transmitting a relatively great Iamount of power for its size.

Still another object of the present invention is to provide a novel skew axis reduction gearing unit including a plurality of worm gear and worm'sets wherein one Worm andgear set may be adjusted relative to another worm and gear set so that one set irons out or eliminates any errors in the other set when the sets are run together.

Other objects and advantages of the present invention will become'apparent from the following description andl the accompanying drawings wherein:

Fig. 1 is a sectional view taken along line 1-1 in Fig. 2 and shows a reduction gearing unit embodying one form of the present invention;

Fig. 2 is ra sectional view taken along line 2 2 in Fig. l;

Fig. 3 is a fragmentary sectional view showing a reduction gearing unit embodying another form of the present invention;

Fig. 4 is a sectional view taken along line 4 4 in Fig. 3;

Fig. 5 is a partial sectional view taken along line 5-5 in Fig. 6 showing another modified form of the present invention;

Fig. 6 is a partial sectional view taken along line 6-6 inFig. 5; and

Fig, 7 is a fragmentary sectional view showing another embodiment wherein the worm gear sections are interconnected.

There are many machines and appliances wherein it is desired to drive a plurality of concentric and telescopically associated shafts, and in accordance with the present invention, this may be accomplished with'a gearing unit such as the gearing unit 10 shown in Figs. l and 2. The unit 10 includes a housing 12 having bearings 14 and 16 mounted in opposite Walls thereof for rotatably supporting a drive shaft 18. The shaft 18 extends from the housing and may be driven by any suitable means such as a motor 20. The shaft 18 carries a pair of axially spaced Worms 22 and 24 hereinafter-more 2,908,187 Patented Oct. 13, 1959 ICC fully described, which worms respectively mesh with face. type worm gears 26 and 28. The gear 26 is secured to an end flange 30 of a hollow driven shaft 32 by a plurality of screws 34. The shaft 32 is journalled in a bearing 36 mounted in a wall of the housing 12. Extending through the hollow shaft 32 is a second shaft 38 to be driven, which shaft 38 is journalled by a hub portion`40 of the gear 26 and a bearing 42 mounted in the housing. The gear 28 is secured to a' ange 44 on the shaft 38 by a plurality f screws 46.

The axes of rotation 48 and 50 of the Worms and worm gears respectively are skew axes or in other words, they are non-parallel and non-intersecting. It should be noted that the worm shaft 48 is arranged so that Vthe distance between the axis 50 and a point 52 at which line 54 in a plane coincident with the axis 50 and perpendicular to the axis 48 intersects the axis 18 is less than the radii of the worm gears 26 and 28. In addition, it should be noted that the worms 22 and 24 are frustums of cones having only a moderate taper. The worm 22 is positioned at the left of the line 54 as viewed in Fig. l and tapers so that the point 56 of a projected cone coincident with the roots of threads 58 on the worm 22 lies on the axis 48 at the right side of the line 54. The worm 22 may b'e provided with a single or multiple start threads, which threads have a plurality `of complete convolutions and are right-hand threads adapted to mate with teeth 60 on the gear 26. Thus, the worm 22 serves to drive the gear 26 in a vcounterclockwise direction as Viewed in Fig. l.

The worm 24 is similar to the worm 22 in that it is formed so that the point 62 of a projected cone coincident with the roots of its threads 64 lies on the `axis 48 at a side of the line 54 opposite from the worm 24. 'lhe threads 64 also have a plurality of complete convolutions and may be either single or multiple start threads. These threads are left-hand threads and are adapted to engage teeth 66 on the gear 28 for driving the gear 28 in a clockwise direction.

Preferably, the worms and gear sections are formed so as to provide a relatively high reduction ratio such for example, as a reduction ratio of at least 9 to 1. The worm and gear sets may be constructed so that they have either the same or different reduction ratios. For certain installations, the outer or larger diameter worm and gear set may have a higher reduction ratio, 4but it should be particularly noted that the inner or smaller diameter worm and gear set may be constructed so as to have a higher reduction ratio than the outer worm and gear set, if desired.

Reference is hereby made to my Patent 2,696,125 dated December 7, 1954 for a complete disclosure relating to the shape of the worm threads and the gear teeth. It suices to state herein that the Worm threads have a consta-nt axial lead and are of uniform cross sectional shape throughout their lengths and are formed to mate with gear teeth having a substantially ideal cross sectional shape throughout their lengths, or in other words, having no appreciable inoperative llets or undercuts. In addition to permitting the provision of high reduction ratios, such worms and gears have several advantages including the ability to transmit relatively great amounts of power as a result of the Ilarge area of contact between the thread and the gear teeth, and -in that the worms and gears may be economically manufactured.

With the structure described above, some error is permissible in locating the wor-m and worm gear shafts relative fto each other since the worms may be brought into proper meshing engagement with their associated worm gears by mounting them on the shaft 18 so thatthey are 3 adjustment relative -to each other.y More. specically, .in the embodiment illustrative in IFigs. 1 and 2, the worm gear 28 is made adjustable relative to the worm gear 26 .by v.forming lthe `apertures-68zthrough Vwhich ithe .screws ..46 extendoverside. ortarcuate vslots so that uponJ-loosening of the .screwsl 46, the gea`rr-28v may .be :rotatedtoa desired .adjfustedpo'sition relative .to the gearl26.. `After .this hasbeen accomplished, .theigear ZASlis again #locked l' .with respect-.to .the shaft.V 38- by .ftighteningfthe screws. -With this structure .the worm may 4be .assembled fwith' the ygears by :first locating lthe .worm 'shaft 48 v.by means `o'fthe bearings` 14..and :16 and. 'shims i 7.0 and '72so. thait-the threads 58 on the worm 22 mesh.properlyawitlntheteeth .f60..on.,the'.gear- 26. ThenAthe gearZS. 4maybe-adjusted 4in'flthe manner .just described relativeltoithe. .gear-126 iuntil the. teeth 16.6 properly..mesh..with the. threads `.64. flnathis .Way both worm and .gearsetsmay :beieasilyvbrought Iinto .proper .meshing relationship. 1i Furthermore, afterethe `gears have ybeen run for a .period ofrtimeranydadjustment madenecessary as aresult of wear.or.any.other reason .may be easily made to insure .proper operation.

'In Figs. 3.and .4 thereis shown. amodiediform of the `present inventionv which lis `similar to the-abo,ve de- .scribedfstructure as indicated by the .applicationof.ident-ireal reference numeralsiwith the sulTX "wa'dded-to .corresponding elements, .Thisembodiment diers-/in-that-f'the worm 24a is disposed at the same lside ofthe line-.54a .as .the wormV 22a 4and is also. provided with right-hand threads. As =a result, this structure-.is adapted .todi-.ive 'the worm rgears 26a .and.- 28a.in .thesamedirection o Fun lrthermo're, in this embodiment the AWorms` are Lmounted so `thattheyrnaybe easily adjusted axiallyiandalso rotatably adjusted relative to each other. `In order t-obtain I-axial adjustment, a positioning screwi 74 Lis Athreaded.into

-the housing-..and. .supports a bearing 76.rfor locatingthe .right-.hand end of the .Wormshaft 18a, and asimilatlposi- A.tioning screwsZS carryingabearing 80 threadedlthrough -`bracket 48 2 orengaging the left-hand end ofthe worm shaft. Any. suitable motordrive means including 'a pulley fr84may be provided 4fordriving the shaft 18a. 'I The worms 1:22a .and 24a are clamped; between a.shoulder-86=.on..the

Worm shat and a nut member 88lthreaded ontolthe shaft :so `.that they 4are normally locked againsthrelative-irotationf f with .respect .tojeach otherandtheshaft. However,lupon .loosening of thek nut the .worms may `be rotated andadjusted; relative 4to each other. Preferably, lthe-.worms are axially separated-by a shim 9.0, .and it .wil-l be appreciated ).thatetheworms may be adjusted axially relative `to reach other by changing the thicknessof the shim. Itshould also :be understood that, if'desired,..the wormgears' 26a -and 28h mayzalso be mountedisothat .they Amay be rof rt-attively adjusted relative to each` other ina .mannersimlar to the above described worm gears, and in addition, the

above ,described `worms 22Y and: 24 may beemounted so that rgthey may ibe adjusted .axially and `rotatively'relative to each other-in a mannersimilar to hthe wormsfZZa -and24a.

worm ZZb Lvand its associated worm gear`26b eare. essenf tially identical to rthecorresponding elementsof .the above the tapered wenn and face;type Agear, contemplated vherein ..shouldnot beused whenthe gear ratio is tofbie -.less.than

.about 9. Therefore, the lstructure VVshown Vvin Figs 5 ,and -`,6 may tbe :usedto gadvarrtageyvhen Ait ,-isgdesired.` lto ...have-thegear ratio of the wom-.24111 andigear -28b1less Y than 9'.

... cis-drive edueentrie Shafts. .32h ..Iidb,zwhielrtextend .ep-

positely .from eachother. However, itis understeedthat these shafts may be telescopically associated in a manner similar to the shaft described' above. Furthermore, in this embodiment the gearing unit is provided with clutch means so that the shaft 32b and 3811 maybe selectively driven. More specifically, the hub of the worm gear 28h which is freely rotatablydisposed on the shatt`38b is provided with.lelutcllrteethA 92,`ad^ apteld\t o interengage with teeth 94 on'a clutch member 96 axially slidable on the 1o shaitb fha-t rretaiuedragaihstexitation relativer/inthe shaft by. a key 98., w Similarly, the .gearr 2.6fb which vfreely rotatable .en theehaitMbiS.provided .with ,eluteh teeth 0 adapted" to interengage with clutch' teeth`102'on an axially slidable iqlutchgmembergilg@ key 106 is provided for preventing relative rotation between the clutch member 164 and -the shaft'32b. Any suitable means including a lever 108 pivotally mounted as at 110 is provided .for shiftingwthe Clutch-:member ihteaand `Qutof ,engagement:withir the :.gear 811m hieh leiterhas.. a bifurcated end portion 112 carryingfpinsg 115i projecting finte. an ,annular slet 11.6 inthe elutehmerrlber. z :Al Similar suitably nperated fleyer 11,8 .isiprorided for Shifting .the Lehrte .emhe gearz 26h. .mndifyithestructures described,

gear sets may bentilizedt drive a single Shaft.. Y'Ihis, may be accomplished hy rigidity tereenueetingthe sha s zb and: -71:8!) 4oreby replaeinsithese shafts` fwithpa` Siugleehaft .zrIt-tismiddurse; 'Understoodethatfthe warms shxwugin FisS -Sand-,.6 ,may ,he meunie for axialahdretativeadiu tinent relative to.; eaeh lotller-,lrl amender .simil te `that :.described shove in .eanneetion withsthe embodiment Aof Figs- -3 ,and .4- infin. 7 vvlteneiil .elements correspondingatotthosedescribed above vare;de.signated; :by the: Same -netereneelnu- :metals with the. :suiX ffc' addedgthere isishown. :aiunit similar to the gearing unit of Figs. 3 and 4 exceptgthat tithe gear. seeti0.n,S-.are..tixedtogether .una Singletshaftand are .adapted ato. ;be driven in;,11 11,is0`n.` tOi-.(:ODI-Se; the` .two 10 .i l vitorlrl and ,gear sets of ,embodiment are :constructed so.as :to havelthe,sanieireduetion ratio.;1n border. ,to iaeilitate proper meshing-,and .adjustment thev .wor-ms Maand '2(40 .with lnespeet .to thegearisectionsr adjustable mounting .means :similarroithat ,shovvnin:Figs. .Y 3,. andA is 45..p1;Qvided,. .and Vthe .gear section ;i 28e. may.; b

securedto the gearssection 21.16.01.bysCreylsiAQc.extending through sletsac. and. threaded into. :.thesgear With 1. the; driyent gears. as .well as e the .driving'r worms'.v locked together asin this embodiment, eachrgear .fsettseryesas a 50. .central eter thennther sof-.that *..oneltset ffirons. ont? or Y eliminates any errors in the other set. From-.thegabove description itjsseenlthatzthe .present invention'thas'proyided ainoyelpskeiw. axismduction gear- Y ing unit including a plurality of congentrjctyromlgear 55,; seetiens-,and atfnluralityiof mormsrotatable about aligned axes in a common plane so that the unit is very compact 1 whi1e.;is.til1 :providing .a ihighireduction rratio.- L It .is A.also seenithatl this inventicnhas providedzalskew, axisgiredllction gearing unit of compact construction whichtisicapable 601 -Of.driving Lgear Sect-ions. yeither in, .thesameorl in ,the opposite directions and either at the same oriat. .widely..dif Yierentspeeds. I-Furthenmore, fit-wiklgibe appreciatedlhat :.-with `.amovel `gearing .unit oijtthe V,present invention, l )large amounts of power may be transmitted to thedxiven Vshafts V' without.undulytilcreasingsthe `Size of ..t;heA unit. Jnz addi- .tionmit is .seer1;th at the .wormgand gearfsets maybe adjusted sothat v.each ,serves to eliminate any errors inthe athenv Y i Q While the` `preferred embodiments of thefprese`nt,in- `vention` have been,.shown iand .described herein, it is;.o.b viens that many structural details `mayxb'ejchanged without `.;;c 1epar,ting'from the. spirit and scgpeftofrtheappended claims. y'

-T;hr.i vention yisclairrljed as follows: 75 1- Aifreiiuetionngearing...unitrgcomprising arotatably diustably mounted relatively large face-type worm gear, a second and relatively smaller similar face-type worm gear concentric with the relatively large worm gear, a power input shaft, a rst Worm ixed on said power input shaft `and meshing with said relatively large worm gear and in skew axis relation thereto, said first worm being of uniform lead and having a rectilinear taper, a second worm fixed on said power input shaft for rotation coaxial with said first worm and meshing with the smaller worm gear, said second worm being of uniform lead and having a rectilinear taper, said second worm and smaller worm gear being in skew axis relation, -the common perpendicular to the 'Worm axis and the gear axis being sholter than the radius of the larger worm gear, said rst and second worms being axially spaced apart a substantial distance to engage said rst and second worm gears in different quadrants thereof, the taper of said first and second worms being relatively reversed, and means mounting the rst and second Worm gears for relative rotation so that the first and second gears rotate in relatively opposite directions.

2. A reduction gearing unit comprising a rotatably mounted relatively large face-type wonn gear, a second and relatively smaller similar face-type worm gear concentric with the relatively large worm gear, a first worm meshing with said relatively large worm gear and in skew axis relation thereto, said first worm being of uniform lead and having a rectilinear taper, a second worm fixed for rotation coaxial with said rst worm and meshing lwith the smaller Worm gear, said second worm being of uniform lead and having a rectilinear taper, said second worm and smaller worm gear being in skew axis relation, the common perpendicular to the worm axis and the gear axis being shorter than the radius of the larger worm gear, said first and second worms being axially spaced apart a asume? large worm gear a power input shaft traversing the faces of said iirst and second Worm gears, means affording endwise adjustment of said power input shaft, a rst worm xed on said power input shaft and meshing with said relatively large worm gear in skew axis relation thereto, said rst worm being of uniform lead and having a rectilinear taper, and a second worm iixed on said power input shaft for rotation coaxial with said lirst worm and meshing with the smaller worm gear, said second worm and smaller worm gear being in skew axis relation, the common perpendicular to the worm axis and the gear axis being shorter than the radius of the larger worm gear, said first and second worms being axially spaced apart a substantial distance to engage said rst and second worm gears in diterentquadr'ants thereof.

References Cited in the le of this patent UNITED STATES PATENTS 283,079 Conradson Aug, 14, 1883 1,323,282 Horton Dec. 2, 1919 1,848,342 Gleason Mar. 8, 1932 2,028,148 Elbertz Jan. 21, 1936 2,418,555 Kirsten Apr. 8, 1947 2,696,125 Saari Dec. 7, 1954 

